1. Field of the Invention
The present invention relates to a vehicle rotary electric machine for a passenger car, a truck, etc.
2. Description of the Related Art
Recently, in order to solve environmental problems, various efforts to reduce idling rotation speed of a vehicle and vehicle weight for improving fuel consumption, and to narrow the engine compartment for increasing the passenger compartment have been made. As a result, the vehicle rotary electric machine that is driven by an engine has been required to reduce the size and to increase the output power thereof. In order to meet the above requirement, U.S. Pat. No. 5,998,903 or its basic application, JP-A-2000-69729, discloses a vehicle AC generator. In this vehicle AC generator, a stator winding is formed from a plurality of conductor segments, and conductor segments that extend from different layer of different slots are connected, in order to increase the space factor of, or decrease the resistance of, the stator winding.
On the other hand, the engine compartment of a running vehicle, where the vehicle rotary electric machine is mounted, is subjected to foreign particles including electrolyte, such as car shampoo or saltwater, and dust. Particularly, because the vehicle AC generator is cooled by a fan, electrolyte or foreign particles may reach the inside of the vehicle AC generator. Thus, it is important to protect the stator core against such environmental hazard.
The vehicle AC generator disclosed in the above publication, the stator winding in which a plurality of conductor segments is welded together at joints of winding. Therefore, temperature of the joints of winding becomes high. For example, if the joints of winding are coated with insulation film, the insulation film may deteriorate due to thermal stress applied while the joints of winding are welded, resulting in peeling off or cracking of the insulation film. Accordingly, electrolyte or other foreign particle may enter the gaps formed due to the peeling or cracking and stay there. If the insulation film coats the gaps, it may be mingled when the joints of winding are welded. Therefore, the joints of winding are not stable, and electrolyte or other foreign particle may enter the gaps formed between insulation films due to peeling or cracking and stay there. In order to improve insulation performance, the joints of winding are coated by additional insulation film. However, if the additional insulation film peels off or cracks due to deterioration caused by thermal stress, the joints of winding are not sufficiently maintained. Moreover, when the joints of winding are welded, the segment ends of the conductor segments melt, brim over in circumferential and radial directions and solidifies again. Therefore, the distance between the joints of winding aligned in a ring becomes so narrow that the joints of winding may be short-circuited.